Ethnobotanical study of the wild edible and healthy functional plant resources of the Gelao people in northern Guizhou, China

Introduction The Gelao people are a unique minority in Southwest China with a unique culture for the utilization of edible plants, including a large number of medicinal plants. They believe that at least 61 species are edible and have medicinal value. Ethnobotany research can reveal the local knowledge of the Gelao people regarding the traditional use of plants and the relationship between this minority and their living environment to help retain and pass on this traditional knowledge forever. Methods Edible wild plants and their applied ethnic knowledge were investigated in three counties in northern Guizhou. Gelao residents were the main informants, and literature search, village interviews, participatory observation and quantitative ethnobotany evaluation were used. Results A total of 151 species of wild plants in 67 families are collected and eaten by Gelao residents, among which 61 species were considered to have medicinal value, accounting for 40.4% of the total, and 43 were listed in the Chinese Pharmacopoeia. There were 57 plant species with fruits as their edible parts, which are consumed as snacks, followed by 54 species whose young seedlings and leaves are the edible parts, most of which are consumed cold or stir-fried. Other edible parts included roots or rhizomes (bulbs), flowers, whole plants, seeds, fruiting bodies and stems. There were two consumption modes: raw and cooked. Raw foods were mainly consumed as snacks, which mainly comprise fruits. Cooked foods were mainly vegetables consumed cold or stir-fried. Some plants were used as seasonings, infused wines, condiments and grains. The main medicinal functions were nourishing and reducing heatiness. Nourishing plants were mainly “shen” plants and Liliaceae, while plants able to reduce heatiness were mainly Asteraceae. Others functions included anti-hangover, anticancer and insecticidal. There were 38 species of important edible wild plants (CFSI > 500) in northern Guizhou, which had a high utilization rate. Houttuynia cordata Thunb. and Mentha suaveolens Ehrh. were the most representative edible wild plants in this area. The species, edible parts, edible categories, consumption modes and medicinal functions of edible wild plants in this area are diverse, and the traditional knowledge on their uses is rich. However, the number of wild plant species eaten by the informants and their related knowledge were positively correlated with age, which indicates that the rich traditional knowledge in this area is gradually disappearing with urbanization. Conclusions The Gelao have a rich history of consuming wild plants. With the development of the social economy, the traditional knowledge passed from older generations is gradually being lost and its inheritance is facing great risks. This study collects, sorts and spreads this precious traditional knowledge, which is of great value to its protection and inheritance and fully demonstrates the value and importance of our work.


Background
Wild plant resources play an indispensable role in the history of human development [1]. They are not only used to fill gaps in food supply caused by drought or resource shortages but also play an important role in maintaining the livelihood security of people in resource-deficient areas and in balancing the nutritional value of diets [2,3]. With globalization, the food crisis has become prominent, and edible wild plant resources, especially those with a long tradition of use as food, will become an important supplementary food source for humans [4,5].
The Gelao people are a unique minority in Southwest China, of whom more than 90% live in the northern part of Guizhou Province [6]. The mountainous geographical environment and abundant precipitation make this area rich in wildlife diversity [7], with many rare, endemic and ancient groups preserved. Northern Guizhou is one of the key land biodiversity areas in China given its high concentration of important biodiversity groups, which also has international significance [8,9]. At the same time, the mountainous geography leads to a lack of sufficient cultivated land in this area. As a result, abundant wild plant resources have become an important supplementary food source for the Gelao people [10]. Over their long history, the Gelao people, combining their environmental conditions, religious beliefs and cultural customs, formed a unique traditional food culture and accumulated rich traditional knowledge on the utilization of wild plant resources [11]. This traditional knowledge on the available wild plant resources has a great influence on the protection and sustainable development and utilization of regional biodiversity [12,13]. However, the Gelao people have no written language, and their traditional culture is thus mainly spread by word of mouth [6]. This mode of communication is easily thwarted by urbanization. With the rapid development of China's economy and information technology, the relocation of ethnic minorities is also accelerating, and the rich ethnic knowledge accumulated for thousands of years by ethnic minorities without their own written language is rapidly disappearing [14,15]. This is no exception for the Gelao nationality. Therefore, a new way for communicating the traditional knowledge of the Gelao people is needed.
Through ethnobotany research, we can understand the local knowledge of Gelao people regarding the traditional use of plants and the relationship between Gelao people and their living environment in order to retain and pass on this traditional knowledge forever. At the same time, we can also explore wild plant resources with high utilization value, discuss their development value and provide appropriate suggestions for protecting biodiversity and sustainable development and utilization of wild resources in minority areas.

Study area
In this study, Daozhen County, Wuchuan County and Zheng 'an County in northern Guizhou are taken as the study areas (Fig. 1). This region spans 28°9′ to 29°13′ N, 107°4′ to 108°13′ E. It is located in the southeast, middle and east of Dalou Mountain and the upper reaches of the Furong River. It has a subtropical humid monsoon climate and a mid-subtropical humid monsoon climate; its average annual temperature is 8-16.14 °C, and the annual precipitation is 800-1400 mm. This area is a multiethnic settlement, and the main Chinese ethnic groups are the Gelao, Miao and Han (Table 1). Typical traditional agriculture in mountainous areas and industrial parks is the mainstay, and the main crops are corn, rice, potato, tea, pepper, Chimonobambusa quadrangularis (Franceschi) Makino and other Chinese herbal medicines, such as Codonopsis radix, Bletilla striata Rchb. f. and Pseudocydonia (C. K. Schneid.) C. K. Schneid. This area is located in the intersection zone between Guizhou and Chongqing, which is an important economic and cultural intersection area between southern Chongqing and northern Guizhou and has developed a unique diversified local culture.

Ethnobotanical information collection
In the field investigation process, key-person interviews, semistructured interviews and participatory rural evaluation methods were adopted, and the basic content of interviews followed the "5W + 1H" question pattern [16]. This helped to uncover the traditional knowledge of edible wild plants and record, sort out and analyze the basic information provided by informants as well as the local common names, edible parts, edible categories, consumption modes and medicinal functions of edible plants. The participatory observation method was used [17] to understand the species, uses, functions, edible parts and edible methods of wild plants collected and eaten in the daily life of the local people.
Video telephone interviews were also conducted, and the interview content was the same as that of the field survey.

Ethnobotanical quantitative evaluation method
The cultural food significance index (CFSI) was used to evaluate the edible wild plants in this area.
where FQI is the frequency of quotation index, AI is the commonness index, FUI is the frequency of utilization index, PUI is the parts used index, MFFI is the multifunctional food use index, TSAI is the taste score appreciation index, and FMRI is the food medicinal role index [18]. According to the Common Research Methods of Ethnobotany [17], these indices are graded and assigned as follows: Frequency of quotation index (FQI): the number of people who mentioned a plant among all informants; Availability index (AI): divided into very common (4.0), common (3.0), average (2.0) and uncommon (1.0); Frequency of utilization index (FUI): divided into more than once a week (5.0), once a week (4.0), once a month (3.0), more than once a year but less than once a month (2.0), once a year (1.0) and unused for nearly 30 years (0.5); Parts used index (PUI): divided into whole plant (4.00), overground and underground parts (3.00), tender leaves and stems and leaves (2.00), flowers and fruits (1.50), tender roots, stems and stipules (1.00) and buds (0.75); Multifunctional food use index (MFFI): divided into raw food and cold salad (1.5), boiling, stewing and seasoning (1.0), special purpose and condiments (0.75) and raw food as snacks (0.50); Taste score evaluation index (TSAI): divided into excellent (10.0), very good (9.0), good (7.5), fair (6.5), poor (5.5) and very poor (4.5); Food-medicinal role index (FMRI): divided into very high (as medicinal food: 5.0), high (as medicine to treat a certain disease: 4.0), moderately high (very healthy food: 3.0), moderately low (healthy food, unknown efficacy: 2.0) and unknown or possibly toxic (1.0).

Specimen identification
In the process of investigation, we collected the first recorded specimens and recorded the collection time, detailed place names (including latitude, longitude and altitude), and local and Latin names of the plants. Specimens were identified based on the electronic version of the full text of the Flora of China (http:// www. iplant. cn/ frps) [19], the Illustration of Flowering Plants in Hengduan Mountain [20] and the Field Identification Manual of Common Plants in China, Hengshan Book [21]. Plants collected during the study were identified to the species level, specimens were prepared and sorted, and collected information was analyzed and visualized using charts. Voucher Specimen numbers are provided in Table 2, and the specimens were deposited in the Life Science Museum and Pharmacognosy Teaching and Research Section of Zunyi Medical University.

Basic information from reports
The age distribution of the 174 informants was divided into age groups. The results showed that all informants were aged between 17 and 89, including 15 informants aged between 17 and 25, 24 between 26 and 30, 18 between 31 and 35, 33 between 36 and 45, 47 between 46 and 55, 18 between 56 and 6, and 19 between 65 and 89. There were 89 males and 85 females, with a male-tofemale ratio of nearly 1:1. There were 147 informants of the Gelao nationality (accounting for 84.48% of the total), 21 of the Miao nationality and 6 of the Han nationality. The results show a positive correlation between the species of wild plants eaten by the reporter and age, and with the increase in the reporter's age, the number of edible plant species and corresponding information that can be provided were more abundant. This pattern is consistent with our earlier research on edible wild plant resources in Hasi Mountain [22]. A total of 16.40 species of wild plants have been eaten by 15 informants under the age of 25, most of which are common wild vegetables or fruits, and most of the informants only know the local names of plants and can provide less information about specific plants and eating methods. However, 19 informants over 65 years old have eaten as many as 66.05 kinds of wild plants per capita, which is 4.03 times that of informants under 25 years old, and some special knowledge is only known by elderly individuals, but no one has made use of this knowledge to prepare special foods, such as using wild fruit to make wine and using Vitex negundo L. and other plants as condiments to make sauce (Fig. 2).

Sources of Gelao edible wild plants in northern Guizhou
The edible plants in Gelao people's residential areas in northern Guizhou were statistically analyzed. Incomplete statistics showed that there were 151 species (varieties) of traditional edible wild plants in this area, belonging to 67 families, with Asteraceae, Rosaceae and Poaceae being the most abundant families, with 16, 13 and 8 species, respectively ( Table 2). Among the 16 species of edible wild plants in Asteraceae, the edible part of Dendranthema indicum (L.) Des Moul. is the inflorescence, whereas in all the other plants, the tender seedlings and leaves are the edible parts. Among these plants, several are mainly used to make a kind of food called "Ba, " such as Gnaphalium affine D. Don, Artemisia lavandulifolia DC., and Artemisia indica Willd (Fig. 3). Regarding the 13 edible wild plants in Rosaceae, the fruits of most are the edible part, and they are mainly consumed as snacks. Lamiaceae, Campanulaceae and Apiaceae also had a good number of edible species. Asparagaceae, Moraceae and Araceae each had four edible wild species. However, Araceae may contain more edible species, but it               was difficult to distinguish them during the investigation (Fig. 4).

Edible parts of Gelao edible wild plants in northern Guizhou
Among the 151 species of edible wild plants, fruits (including young fruits) were the most common edible parts, with 57 species. Trees and shrubs were the main types of plants, and they were most frequently consumed as snacks. Most of the preserved fruits have poor taste or are abundant but not easy to preserve, such as Rosa roxburghii Tratt., Chaenomeles speciosa (Sweet) Nakai, and Ficus carica L. The fruits used for making infused wine cannot be eaten directly, but they have specific medicinal functions, such as Rosa laevigata Michx. and Taxus wallichiana var. chinensis (Pilg.) Florin. There were 54 species of young stems and leaves (tender leaves, tender seedlings, tender buds) consumed, most of which were consumed cold or stir-fried. Most of the plant types are annual herbs or perennial herbaceous plants that die in autumn and winter and grow new buds in spring, represented by Asteraceae and Apiaceae. In addition, the  edible parts included roots or rhizomes (bulbs), flowers, twigs, whole plants, and fruiting bodies. There were two consumption modes: raw and cooked. Raw foods were mainly consumed as snacks, which mainly included fruits. Cooked foods were mainly vegetables, which were mainly consumed cold or stir-fried with young stems and leaves. In addition, the edible wild plants were also used as seasoning, infused wine, condiments, miscellaneous grains, etc. Some plants had many edible parts, such as Allium macranthum Baker and Pyracantha fortuneana (Maxim.) H.L. Li. (Table 2). Some plants are named after the foods that they can be made into locally. For example, Doufuchai (Premna microphylla Turcz.) means a plant that can be made into tofu (Fig. 5), and Bing Fenzi (Nicandra physalodes (L.) Gaertn.) means that the seeds of this plant are mainly used to make a summer-heatrelieving drink.

Medicinal function of Gelao edible wild plants in northern Guizhou
Among the 151 species of edible wild plants counted, there were 61 species that local residents believe have medicinal value in addition to edible value, accounting for 40.4% of the total (Table 2). Medicinal functions mainly included nourishing and reducing 'heatiness, ' and for most of the nourishing plants, the roots were the edible parts. Local residents refer to the plant roots with nourishing effects as "shen," such as tangshen (Codonopsis radix), paoshen (Adenophora stricta Miq.), tutangshen (Campanumoea javanica Blume), turenshen (Talinum paniculatum (Jacq.) Gaertn.) and hongshen (Phytolacca americana L.). Edible plants used for reducing heatiness and relieving summer heat were mainly herbaceous plants, including some vines and trees whose edible parts were the flowers and leaves. Plants whose leaves and flowers are soaked in water for drinking are collectively called "tea, " such as KuDing tea, Tian tea and JinYinHua tea. Apart from general nourishing effects, a few edible wild plants also have some special nourishing effects. Generally, nourishing foods are used to make stews or infused wine with chicken, pork ribs and pig trotters, such as stewed chicken with DangShen and stewed pork ribs with paoshen. Special nourishing plants include Yang-tonifying plants (to improve male sexual function) and brain-nourishing plants. Generally, Yang-tonifying plants are used to make infused wine and drunk, such as Jinyingzi and Yinyanghuo, and brain-nourishing plants are mostly seeds and kernels, such as Hetao. Heatinessreducing edible wild plants are mostly eaten cold or drunk as tea, such as Ma Lan, Pugongying, and Jinyingzi.

Quantitative evaluation of Gelao edible wild plants in northern Guizhou
The comparison results of the cultural food significance index (CFSI) of Gelao edible wild plants in northern Guizhou are shown in Table 3 and

Discussion
Guizhou Province, located in southwest China, has abundant rainfall and changeable terrain. The special geographical environment has created a suitable environment for plants, and a wide variety of plant resources have also provided abundant food resources to local residents [10]. The results show that, compared with our previous research results on edible wild plant resources in arid areas of northwest China's Loess Plateau (Hassan area), the edible wild plant resources collected in the concentrated areas of the Gelao people in northern Guizhou are much richer in species, edible categories and consumption modes. The Gelao people have rich traditional knowledge of plant identification, medicinal uses and resource protection.

Gelao people's botanical understanding of edible wild plant resources
Based on long-term experience, the local Gelao people have accumulated a wealth of traditional knowledge on the rich and varied local edible wild plant resources, not only in terms of their use as food but also as medicine.  The main purpose of cultivation is to facilitate eating, but it is also an effective protection strategy for these frequently eaten resources. Local residents also consciously protect some rare plants. For example, the whole plant of G. elata Blume is not dug, and a certain number of provenances will be reserved so that this valuable medicinal and edible plant resource can sustainably provide food for residents. The collection of E. borealiguizhouense S. Z. He & Y. K. Yang has gradually changed from the previous whole-plant digging to the method of collecting leaves and keeping roots. For plants whose roots are eaten, residents basically follow the principle of picking large ones and keeping small ones. At the same time, they will consciously spread the seeds of rare plants to help their population expand, such as Codonopsis radix, T. paniculatum (Jacq.) Gaertn., and L. brownii F.E.Br. ex Miellez. (pearl bud).
Through combining 23 reports which have been published, it is found that the research areas are mainly in Guizhou, Yunnan, Inner mongolia, Gansu, Fujian, Sichuan Province and Tibet. There are 1,912 kinds of edible ethnic plants in these places. Compared with the 151 kinds of wild edible plants collected in Gelao area in northern Guizhou, we have investigated 66 kinds of wild edible plants that have never been published before, such as Youngia japonica (L.) DC., Symphyotrichum subulatum (Michx.) G.L.Nesom, Rubus idaeus L., Rubus coreanus Miq., Nicandra physalodes (L.) Gaertn. and Indocalamus tessellatus (Munro) Keng f., which are mostly local plants of Gelao nationality.

Current status of the Gelao people's traditional cultural knowledge
Although the informants were mainly Gelao people, we found that there was no considerable difference between the residents belonging to this ethnic group, their Miao and Tujia neighbors, and the local Han people. This differs from the ethnic groups in northern China, such as Tibetans and Mongolians, who have their own characteristics [31,32]. The traditional cultural knowledge of the Gelao people is basically only displayed in festivals or performances for travelers. Their knowledge of the uses of wild plant resources is no different from that of the local Han people. The 151 species of edible plants cited by the Gelao informants are found in various recipes or other works by the Han people [10,33]. The ethnic characteristics of the Gelao people have thus basically died out. At the same time, we also found that the amount of information provided by the informants was positively correlated with age. Most young people under the age of 25 only know that there are certain plants that can be eaten, and they have eaten them before, but they know little about the plants and how to prepare them. In 2020, China has lifted the whole people out of poverty and completely solved the food problem of China Chinese people. Wild edible plant resources of ethnic minorities are mainly used as wild vegetables, condiments or tonics, and only a few varieties are gradually domesticated into daily edible vegetables and become supplementary resources to the existing food resources. But at present, the vast majority of them are only inherited as a traditional culture.

Conclusions
The Gelao people are a special ethnic group living in mountainous areas of northern Guizhou who is affected by a mountainous geographical environment and a shortage of land resources. Their ancestors had the habit of collecting wild plants as food supplements. During the long-term collection and utilization of wild plant resources, the Gelao people have amassed a great deal of traditional knowledge, which has been passed down and accumulated from generation to generation. However, with the development of the social economy, the traditional knowledge passed down from older generations has been gradually forgotten by the younger generations, and its inheritance is faced with great risks. Through ethnobotanical research, we collect, sort and spread this precious traditional knowledge, which is of great value to its protection. The inheritance of the traditional knowledge on plants is as valuable as that of the traditional skills of ethnic groups with unique characteristics varying among countries and regions [34].